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Finding the Fourth Proportional to 203.78, 305.70 and 139.70

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Solution

The fourth proportional to 203.78, 305.70 and 139.70 is: 209.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    203.78 : 305.70 = 139.70 : x
  2. Step 2: Convert to fraction form
    203.78/305.70 = 139.70/x
  3. Step 3: Cross multiply
    203.78x = 305.70 × 139.70
  4. Step 4: Simplify right side
    203.78x = 42,706.29
  5. Step 5: Solve for x
    x = 42,706.29/203.78
  6. Step 6: Final answer
    x = 209.57

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.